MiR-32 contributed to cell proliferation of human breast cancer cells by suppressing of PHLPP2 expression

Overexpression of miR-32 in Chinese hamster ovary cells increases production of Fc-fusion protein

The demand for industrial genetically modified host cells were increased with the growth of the biopharmaceutical market. Numerous studies on improving host cell productivity have shown that altering host cell growth and viability through genetic engineering can increase recombinant protein production. During the last decades, it was demonstrated that overexpression or downregulation of some microRNAs in Chinese Hamster Ovary (CHO) cells as the host cell in biopharmaceutical manufacturing, can improve their productivity. The selection of microRNA targets has been based on their previously identified role in human cancers. MicroRNA-32 (miR-32), which is conserved between humans and hamsters (Crisetulus griseus), was shown to play a role in the regulation of cell proliferation and apoptosis in some human cancers. In this study, we investigated the effect of miR-32 overexpression on the productivity of CHO-VEGF-trap cells. Our results indicated that stable overexpression of miR-32 could dramatically increase the productivity of CHO cells by 1.8-fold. It also significantly increases cell viability, batch culture longevity, and cell growth. To achieve these results, following the construction of a single clone producing an Fc-fusion protein, we transfected cells with a pLexJRed-miR-32 plasmid to stably produce the microRNA and evaluate the impact of mir-32 overexpression on cell productivity, growth and viability in compare with scrambled control. Our findings highlight the application of miRNAs as engineering tools and indicated that miR-32 could be a target for engineering CHO cells to increase cell productivity.

Exosomal miRNA Expression Profiling and the Roles of Exosomal miR-4741, miR-32, miR-3149, and miR-6727 on Gastric Cancer Progression

Objective

Accumulated evidence highlights the biological implications of exosomes in gastric cancer. Herein, we conducted the exosomal miRNA expression profiling and identified potential diagnostic markers for gastric cancer.

Methods

Plasma exosomes were isolated and identified from three gastric cancer patients and three healthy participants. Microarrays of exosomal miRNAs were then analyzed. Differentially expressed exosomal miRNAs were screened with fold − change|≥2.0 and p ≤ 0.05. Among them, miR-4741, miR-32, miR-3149, and miR-6727 expressions were verified in tissues and plasma of patients and healthy subjects. ROC curves were conducted for evaluating the diagnostic performance. The roles of miR-32, miR-3149, miR-6727, and miR-4741 on gastric cancer progression were observed by cellular experiments.

Results

Isolated exosomes were well characterized by Western blot and transmission electron microscopy as well as nanoparticle-tracking analyses. According to the microarrays, 142 exosomal miRNAs were upregulated, and 34 were downregulated in gastric cancer than healthy subjects. miR-4741 upregulation and miR-32, miR-3149, and miR-6727 downregulations were found in tissues and plasma of gastric cancer patients. The AUCs of miR-4741, miR-32, miR-3149, and miR-6727 were separately 0.8554, 0.9456, 0.7683, and 0.8923. Upregulated miR-32, miR-3149, and miR-6727 as well as downregulated miR-4741 lowered proliferative, migratory, and invasive capacities as well as elevated apoptotic levels of gastric cancer cells.

Conclusion

Our study successfully isolated and verified exosomes from plasma of gastric cancer as well as proposed four exosomal miRNAs that could act as promising diagnostic markers and suppress gastric cancer progression.

Prediction methods for microRNA targets in bilaterian animals: Toward a better understanding by biologists

MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression at the posttranscriptional level. Because of their wide network of interactions, miRNAs have become the focus of many studies over the past decade, particularly in animal species. To streamline the number of potential wet lab experiments, the use of miRNA target prediction tools is currently the first step undertaken. However, the predictions made may vary considerably depending on the tool used, which is mostly due to the complex and still not fully understood mechanism of action of miRNAs. The discrepancies complicate the choice of the tool for miRNA target prediction. To provide a comprehensive view of this issue, we highlight in this review the main characteristics of miRNA-target interactions in bilaterian animals, describe the prediction models currently used, and provide some insights for the evaluation of predictor performance.

Characterization of microRNA expression in B cells derived from Japanese black cattle naturally infected with bovine leukemia virus by deep sequencing

Bovine leukemia virus (BLV) is the causative agent of enzootic bovine leukosis (EBL), a malignant B cell lymphoma. However, the mechanisms of BLV-associated lymphomagenesis remain poorly understood. Here, after deep sequencing, we performed comparative analyses of B cell microRNAs (miRNAs) in cattle infected with BLV and those without BLV. In BLV-infected cattle, BLV-derived miRNAs (blv-miRNAs) accounted for 38% of all miRNAs in B cells. Four of these blv-miRNAs (blv-miR-B1-5p, blv-miR-B2-5p, blv-miR-B4-3p, and blv-miR-B5-5p) had highly significant positive correlations with BLV proviral load (PVL). The read counts of 90 host-derived miRNAs (bta-miRNAs) were significantly down-regulated in BLV-infected cattle compared to those in uninfected cattle. Only bta-miR-375 had a positive correlation with PVL in BLV-infected cattle and was highly expressed in the B cell lymphoma tissue of EBL cattle. There were a few bta-miRNAs that correlated with BLV tax/rex gene expression; however, BLV AS1 expression had a significant negative correlation with many of the down-regulated bta-miRNAs that are important for tumor development and/or tumor suppression. These results suggest that BLV promotes lymphomagenesis via AS1 and blv-miRNAs, rather than tax/rex, by down-regulating the expression of bta-miRNAs that have a tumor-suppressing function, and this downregulation is linked to increased PVL.

MicroRNA-32 and MicroRNA-548a Promote the Drug Sensitivity of Non-Small Cell Lung Cancer Cells to Cisplatin by Targeting ROBO1 and Inhibiting the Activation of Wnt/β-Catenin Axis

Background

The roles of microRNA (miR)-32 and miR-548a in non-small cell lung cancer (NSCLC) have been studied. But their influences on NSCLC cells to cisplatin (DDP) resistance remain elusive. This study estimated the mechanisms of miR-32 and miR-548a in NSCLC cells to DDP.

Methods

Differentially expressed miRs in DDP-sensitive and resistant tissues were screened out using a GSE56036 chip. Then the predictive efficacies of miR-32 and miR-548a on DDP resistance were analyzed in NSCLC patients. The target mRNAs of miR-548a and miR-32 were predicted. miR-548a and miR-32 were knocked down to assess the influences of miR-32 and miR-548a on NSCLC growth. DDP-resistant cells were constructed and miR-32 and miR-548a expression was detected in resistant cells. After miR-32 and miR-548a knockdown, the IC50 value of DDP was detected. Then, the activation level of Wnt/β-catenin pathway was detected. The roles of miR-32 and miR-548a in NSCLC growth in vivo were detected by tumorigenesis experiment.

Results

miR-32 and miR-548a were poorly expressed in DDP-resistant NSCLC. miR-32 and miR-548a mimic enhanced the DDP sensitivity of NSCLC cells. Both miR-32 and miR-548a targeted ROBO1, and overexpression of ROBO1 inhibited the promotion of miR-32 and miR-548a mimic on DDP sensitivity. ROBO1 activated the Wnt/β-catenin pathway, thus enhancing the DDP resistance.

Conclusion

miR-32 and miR-548a target ROBO1 and inhibit Wnt/β-catenin activation, thus promoting the drug sensitivity of NSCLC cells to DDP.

Oncogenic role of MIR516A in human bladder cancer was mediated by its attenuating PHLPP2 expression and BECN1-dependent autophagy

Although MIR516A has been reported to be downregulated and act as a tumor suppressor in multiple cancers, its expression and potential contribution to human bladder cancer (BC) remain unexplored. Unexpectedly, we showed here that MIR516A was markedly upregulated in human BC tissues and cell lines, while inhibition of MIR516A expression attenuated BC cell monolayer growth in vitro and xenograft tumor growth in vivo, accompanied with increased expression of PHLPP2. Further studies showed that MIR516A was able to directly bind to the 3'-untranslated region of PHLPP2 mRNA, which was essential for its attenuating PHLPP2 expression. The knockdown of PHLPP2 expression in MIR516A-inhibited cells could reverse BC cell growth, suggesting that PHLPP2 is a MIR516A downstream mediator responsible for MIR516A oncogenic effect. PHLPP2 was able to mediate BECN1/Beclin1 stabilization indirectly, therefore promoting BECN1-dependent macroautophagy/autophagy, and inhibiting BC tumor cell growth. In addition, our results indicated that the increased autophagy by attenuating MIR516A resulted in a dramatic inhibition of xenograft tumor formation in vivo. Collectively, our results reveal that MIR516A has a novel oncogenic function in BC growth by directing binding to PHLPP2 3'-UTR and inhibiting PHLPP2 expression, in turn at least partly promoting CUL4A-mediated BECN1 protein degradation, thereby attenuating autophagy and promoting BC growth, which is a distinct function of MIR516A identified in other cancers.Abbreviation: ATG3: autophagy related 3; ATG5: autophagy related 5; ATG7: autophagy related 7; ATG12: autophagy related 12; BAF: bafilomycin A1; BC: bladder cancer; CHX: cycloheximide; Co-IP: co-immunoprecipitation; CUL3: cullin 3; CUL4A: cullin 4A; CUL4B: cullin 4B; IF: immunofluorescence: IHC-p: immunohistochemistry-paraffin; MIR516A: microRNA 516a (microRNA 516a1 and microRNA 516a2); MS: mass spectrometry; PHLPP2: PH domain and leucine rich repeat protein phosphatase.

Potential miRNAs for miRNA-Based Therapeutics in Breast Cancer

MicroRNAs (miRNAs) are small non-coding RNAs that can post-transcriptionally regulate the genes involved in critical cellular processes. The aberrant expressions of oncogenic or tumor suppressor miRNAs have been associated with cancer progression and malignancies. This resulted in the dysregulation of signaling pathways involved in cell proliferation, apoptosis and survival, metastasis, cancer recurrence and chemoresistance. In this review, we will first (i) provide an overview of the miRNA biogenesis pathways, and in vitro and in vivo models for research, (ii) summarize the most recent findings on the roles of microRNAs (miRNAs) that could potentially be used for miRNA-based therapy in the treatment of breast cancer and (iii) discuss the various therapeutic applications.

MicroRNA-527 Induces Proliferation and Cell Cycle in Esophageal Squamous Cell Carcinoma Cells by Repressing PH Domain Leucine-Rich-Repeats Protein Phosphatase 2

Increasing evidence indicated that microRNAs served dominant roles in carcinogenesis and cancer progression by targeting potential downstream genes. In our study, we found that miR-527 was an upregulated expression in human esophageal squamous cell carcinoma (ESCC) cells and tissues. Furthermore, overexpression of miR-527 promoted cell proliferation and colony formation, enhanced anchorage-independent growth ability, and contributed to cell cycle. In addition, protein phosphatase 2 (PHLPP2) was identified as the direct downstream target gene of miR-527 and was confirmed by luciferase gene reporter assay. In summary, we concluded that miR-527 acted as an oncogenic microRNA in ESCC development by directly targeting PHLPP2 might be a novel therapeutic target for the treatment of ESCC.

Identification and development of long non-coding RNA-associated regulatory network in colorectal cancer

Colorectal cancer (CRC) is one of the leading causes of cancer‐associated death globally. Long non‐coding RNAs (lncRNAs) have been identified as micro RNA (miRNA) sponges in a competing endogenous RNA (ceRNA) network and are involved in the regulation of mRNA expression. This study aims to construct a lncRNA‐associated ceRNA network and investigate the prognostic biomarkers in CRC. A total of 38 differentially expressed (DE) lncRNAs, 23 DEmiRNAs and 27 DEmRNAs were identified by analysing the expression profiles of CRC obtained from The Cancer Genome Atlas (TCGA). These RNAs were chosen to develop a ceRNA regulatory network of CRC, which comprised 125 edges. Survival analysis showed that four lncRNAs, six miRNAs and five mRNAs were significantly associated with overall survival. A potential regulatory axis of ADAMTS9‐AS2/miR‐32/PHLPP2 was identified from the network. Experimental validation was performed using clinical samples by quantitative real‐time PCR (qRT‐PCR), which showed that expression of the genes in the axis was associated with clinicopathological features and the correlation among them perfectly conformed to the ‘ceRNA theory’. Overexpression of ADAMTS9‐AS2 in colon cancer cell lines significantly inhibited the miR‐32 expression and promoted PHLPP2 expression, while ADAMTS9‐AS2 knockdown had the opposite effects. The constructed novel ceRNA network may provide a comprehensive understanding of the mechanisms of CRC carcinogenesis. The ADAMTS9‐AS2/miR‐32/PHLPP2 regulatory axis may serve as a potential therapeutic target for CRC.

Isoliquiritigenin suppresses the proliferation and induced apoptosis via miR-32/LATS2/Wnt in nasopharyngeal carcinoma

Nasopharyngeal Carcinoma is limited by the various severe side-effects and surgery is rarely performed. Iosliquiritigenin has a series of biological activities, such as antiviral, anti-free radical and antitumor. However, the role and underlying mechanism of isoliquiritigenin in nasopharyngeal carcinoma have not been understood yet. Herein, the results revealed that isoliquiritigenin could inhibit cell proliferation in nasopharyngeal carcinoma cell lines, including C666-1 and CNE2, in both Cell Counting Kit-8 (CCK-8) and 5-Ethynyl-2'-deoxyuridine (EdU) assay. In addition, isoliquiritigenin promoted nasopharyngeal carcinoma cell apoptosis, with the up-regulations of Bax, Caspase-3 and Caspase-9 and the down-regulation of Bcl-2. Meanwhile, isoliquiritigenin suppressed nasopharyngeal carcinoma cells migration and invasion with the down-regulation of matrix metalloproteinases (MMP)-2 and MMP-9. Furthermore, the expression of miR-32 was up-regulated in the nasopharyngeal carcinoma tissues, while isoliquiritigenin could significantly down-regulate the expression of miR-32. And over-expression of miR-32 promoted the nasopharyngeal carcinoma cells growth, migration and invasion, and suppressed apoptosis. However, isoliquiritigenin treatment dramatically inhibited the effect of miR-32. Besides, luciferase reporter assay confirmed that large tumor suppressor 2 (LATS2) was a direct target of miR-32. And isoliquiritigenin increased the expression of LATS2, while silencing of LATS2 promoted the nasopharyngeal carcinoma cells growth. Moreover, western blotting discovered that isoliquiritigenin inhibited nasopharyngeal carcinoma cells growth via Wnt signaling pathway. Finally, CNE2 cells transplanted xenografts tumor model in nude mice were performed and it suggested that isoliquiritigenin could inhibit the development of xenografts nude mice, along with the decrease of tumor volume and the expression of miR-32 and LATS2. Overall, isoliquiritigenin was confirmed to be a potent anti-nasopharyngeal carcinoma compound both in vitro and in vivo, and accomplished by regulation of miR-32/LATS2/Wnt.

Predicting MicroRNA-Disease Associations Based on Improved MicroRNA and Disease Similarities

MicroRNAs (miRNAs) are a type of non-coding RNAs with about ∼22nt nucleotides. Increasing evidences have shown that miRNAs play critical roles in many human diseases. The identification of human disease-related miRNAs is helpful to explore the underlying pathogenesis of diseases. More and more experimental validated associations between miRNAs and diseases have been reported in the recent studies, which provide useful information for new miRNA-disease association discovery. In this study, we propose a computational framework, KBMF-MDI, to predict the associations between miRNAs and diseases based on their similarities. The sequence and function information of miRNAs are used to measure similarity among miRNAs while the semantic and function information of disease are used to measure similarity among diseases, respectively. In addition, the kernelized Bayesian matrix factorization method is employed to infer potential miRNA-disease associations by integrating these data sources. We applied this method to 6,084 known miRNA-disease associations and utilized 5-fold cross validation to evaluate the performance. The experimental results demonstrate that our method can effectively predict unknown miRNA-disease associations.

Isocitrate dehydrogenase 1-snail axis dysfunction significantly correlates with breast cancer prognosis and regulates cell invasion ability

Background

The isocitrate dehydrogenase (IDH) gene family expresses key functional metabolic enzymes in the Krebs cycle and mediates the epigenetic reprogramming, which serves as an important biomarker of breast cancer. However, the expression levels of the IDH protein and their biological function in human breast cancer remain largely unknown.

Methods

In this study, the clinical impact of IDH1 expression on the progression and prognosis of breast cancer was evaluated using immunohistochemistry assay (IHC) of the corresponding tumor-adjacent normal, ductal carcinoma in situ (DCIS), and invasive ductal carcinoma (IDC) tissues from 309 patients with breast ductal carcinoma. The relationship between microRNA (miRNA) and IDH1 were examined by a bioinformatics approach, western blot and reporter assay. The biological functions of IDH1 were examined in breast cancer cells with IDH1 knockdown, including proliferation, migration and invasion.

Results

The present findings revealed that the mRNA and protein expression levels of IDH1 were both significantly lower in breast cancer tissues than in adjacent normal tissues. A low expression level of IDH1 in breast cancer significantly correlated with advanced stage (p = 0.012), lymph node metastasis (p = 0.018), and poor disease-specific survival (DSS) (adjusted hazard ratio (AHR), 1.57, 95% confidence interval (CI), 1.08–2.30; p = 0.02). Furthermore, oncogenic miR-32 and miR-92b were identified to suppress IDH1 expression, leading to the inhibition of cell migration and invasion. We further explored whether reduced expression of IDH1 significantly increases snail expression by activating HIFα (hypoxia-inducible factor-1 alpha) and NFκB (nuclear factor kappa B) signaling. Multivariate Cox regression analysis revealed that the combination of low IDH1 and high snail expression could be an independent risk factor for shorter DSS (AHR, 2.34; 95% CI, 1.32–4.16; p = 0.004) and shorter disease-free survival (AHR, 2.50; 95% CI, 1.39–4.50; p = 0.002) in patients with breast cancer.

Conclusion

Our findings revealed that a IDH1^low/Snail^high molecular signature could serve as an independent biomarker for poor prognosis in breast cancer

Electronic supplementary material

The online version of this article (10.1186/s13058-018-0953-7) contains supplementary material, which is available to authorized users.

Exosomal microRNA-32-5p induces multidrug resistance in hepatocellular carcinoma via the PI3K/Akt pathway

BACKGROUND

Multidrug resistance is the main obstacle for hepatocellular carcinoma (HCC) treatment. miR-32-5p is involved in HCC progression but its function in multidrug resistance is still unclear. Here we aim to find out the function of miR-32-5p in inducing multidrug resistance and its underlying mechanisms of transforming sensitive cell to resistant cell.

METHODS

We detected the expression of miR-32-5p and PTEN in the multidrug-resistant cell line (Bel/5-FU) and the sensitive cell line (Bel7402), HCC and para-carcinoma liver tissues through real-time PCR. Dual-luciferase reporter assay verified PTEN is the target of miR-32-5p. Exosomes from sensitive and multidrug resistant cell line were obtained and confirmed through ultracentrifuge and Nano Analyzer. Gain- and loss-of-function experiments, rescue experiments, a PI3K/Akt pathway inhibitor, an exosome biogenesis inhibitor, and nude mice xenograft models were used to determine the underlying mechanisms of miR-32-5p and PTEN, as well as exosomal miR-32-5p in inducing multidrug resistance in vitro and in vivo.

RESULTS

miR-32-5p was significantly elevated but PTEN was reduced in Bel/5-FU. An inverse correlation between miR-32-5p and PTEN was confirmed in HCC cell lines and patients; moreover, high expression of miR-32-5p and low expression of PTEN were positively associated with poor prognosis. Over-expression of miR-32-5p activated the PI3K/Akt pathway by suppressing PTEN and induced multidrug resistance via exosomes through promoting angiogenesis and epithelial-mesenchymal transition (EMT).

CONCLUSIONS

Our study demonstrated that the multidrug-resistant cell, Bel/5-FU delivers miR-32-5p to sensitive cell, Bel7402 by exosomes and activates the PI3K/Akt pathway to further induce multidrug resistance by modulating angiogenesis and EMT.

Inhibition of miR-32 activity promoted EMT induced by PM2.5 exposure through the modulation of the Smad1-mediated signaling pathways in lung cancer cells

Epithelial mesenchymal transition (EMT) is a crucial morphological event during tumor progression. The present study reported that EMT could be triggered by airborne fine particulate matter (PM) with a mean diameter of less than 2.5 μm (PM2.5) in human lung cancer cells. We also aimed to elucidate the possible mechanisms of these processes. The results showed that treatment with PM2.5 promoted the activity of the SMAD family member 1 (Smad1)-mediated signaling pathway and downregulated the expression of the inhibitory Smad proteins Smad6 and Smad7 in lung cancer cells. Moreover, the knockdown of Smad1 suppressed the EMT process induced by PM2.5 exposure. Our data further revealed that miR-32 has a negative effect on PM2.5-induced EMT. The results showed that the expression level of miR-32 was significantly upregulated in the PM2.5-induced EMT process. The knockdown of miR-32 enhances the activity of the Smad1-mediated signaling pathway, which promotes the EMT process induced by PM2.5. Thus, these findings indicate that PM2.5 can induce the EMT process through the Smad1-mediated signaling pathway, and miR-32 may act as an EMT inhibitor in lung cancer cells.

MicroRNA-140-5p inhibits invasion and angiogenesis through targeting VEGF-A in breast cancer

MicroRNAs (miRNAs) have been proven to be involved in cell metastasis and angiogenesis by interaction with the target mRNAs. Evidence has been confirmed that miR-140-5p is a tumor suppressor in human cancers such as breast cancer. However, the potential molecular mechanism of miR-140-5p in breast cancer invasion and angiogenesis is still poorly understood. According to our study, we reported that miR-140-5p inhibited the tumor invasion and angiogenesis of breast cancer cells both in vitro and in vivo by targeting VEGF-A. The mRNA amount of miR-140-5p was decreased in the breast cancer clinical samples and breast cancer with metastasis compared with the corresponding adjacent normal tissues and cancer without metastasis. MiR-140-5p mimics and a negative control were transfected into human MCF-7 and MDA-MB-231 cells. Transwell chambers were used to detect the invasive ability of the cells, and the angiogenic ability was assessed by tube-formation assay. The markers of invasion and angiogenesis, VEGF-A, CD31 and MMP-9, were detected by using immunohistochemistry and western blot analysis in vivo. VEGF-A was verified as a possible target gene of miR-140-5p, and corroborated by dual-luciferase reporter and ELISA. Taken together, the study elucidates the molecular mechanisms by which miR-140-5p inhibits breast cancer metastasis and angiogenesis, and provides a potent evidence for the development of a novel microRNA-targeting anticancer strategy for breast cancer patients.

MicroRNA-32 promotes cell proliferation, migration and suppresses apoptosis in breast cancer cells by targeting FBXW7

Background

MicroRNAs are a class of small non-coding RNAs that are involved in many important physiological and pathological processes by regulating gene expression negatively. The purpose of this study was to investigate the effect of miR-32 on cell proliferation, migration and apoptosis and to determine the functional connection between miR-32 and FBXW7 in breast cancer.

Methods

In this study, quantitative RT-PCR was used to evaluate the expression levels of miR-32 in 27 breast cancer tissues, adjacent normal breast tissues and human breast cancer cell lines. The biological functions of miR-32 in MCF-7 breast cancer cells were determined by cell proliferation, apoptosis assays and wound-healing assays. In addition, the regulation of FBXW7 by miR-32 was assessed by qRT-PCR, Western blot and luciferase reporter assays.

Results

MiR-32 was frequently overexpressed in breast cancer tissue samples and cell lines as was demonstrated by qRT-PCR. Moreover, the up-regulation of miR-32 suppressed apoptosis and promoted proliferation and migration, whereas down-regulation of miR-32 showed an opposite effect. Dual-luciferase reporter assays showed that miR-32 binds to the 3′-untranslated region of FBXW7, suggesting that FBXW7 is a direct target of miR-32. Western blot analysis showed that over-expression of miR-32 reduced FBXW7 protein level. Furthermore, an inverse correlation was found between the expressions of miR-32 and FBXW7 mRNA levels in breast cancer tissues. Knockdown of FBXW7 promoted proliferation and motility and suppressed apoptosis in MCF-7 cells.

Conclusions

Taken together, the present study suggests that miR-32 promotes proliferation and motility and suppresses apoptosis of breast cancer cells through targeting FBXW7.